噁草酮防除直播稻田杂草稻的施用技术

A technique for oxadiazon application in controlling weedy rice in direct-seeded rice fields

为确立噁草酮防除直播稻田杂草稻的施用技术,通过温室盆栽试验比较了噁草酮在不同土壤水分环境下对栽培稻的安全性及对杂草稻的防效,并在大田中比较了不同直播方式下其对杂草稻的防效及栽培稻产量的影响。结果表明,透气条件下,噁草酮对栽培稻的药害最低,但对杂草稻的防效也较差;饱和水分条件下对杂草稻防效较好,150 g(a.i.)/hm^2时其出苗率和鲜重的抑制率达89.61%和61.87%,超过450 g(a.i.)/hm^2时完全抑制出苗;但药后播种对栽培稻安全性较高,600 g(a.i.)/hm^2下对其出苗率和鲜重的抑制率仅分别为38.06%和39.96%,播后施药的药害较重,最低剂量150 g(a.i.)/hm^2时抑制率已分别达88.77%和45.52%;淹水条件下,虽对杂草稻有100%的防效,但也完全抑制栽培稻出苗。大田施用噁草酮300、450、600 g(a.i.)/hm^2,旱直播和水直播方式下杂草稻株防效分别为26.88%、43.54%、44.45%和84.88%、85.74%、90.92%;鲜重防效分别为11.58%、20.16%、27.33%和30.86%、53.68%、80.15%。旱直播和水直播方式下施用量分别超过450、300 g/hm^2时栽培稻产量显著增加。综合分析,推荐水直播整地后泥水状态施用300 g(a.i.)/hm^2噁草酮,水层落干后播种,保持土壤湿润且土表不出现水渍,栽培稻顺利出苗后及时上水且不淹没苗心为宜。

The investigate the technique for applying oxadiazon to controlling weedy rice in direct-seeded rice fields,the safety of cultivated rice and the control efficacy of weedy rice by applying oxadiazon under different soil moistures were compared with pot tests.The field trial was conducted to compare the control efficacy of oxadiazon to weedy rice and yield of cultivated rice under different direct-seeding ways.The results showed that,although oxadiazon caused the lowest injury to cultivated rice under aerobic conditions,the control efficacy against weedy rice was poor.Oxadiazon provided excellent control efficacy to weedy rice under saturated moisture conditions.When oxadiazon was applied to weedy rice at a dose of150 g（a.i.） /hm^2,the inhibition rate of emergence rate and fresh-weight were 89.61%and 61.87%,respectively.When oxadiazon was applied at 450 g（a.i.） /hm^2,there was no emergence of weedy rice.Cultivated rice showed high safety only when sown after oxadiazon spraying.At the highest dose of600 g（a.i.） /hm^2,the inhibition rate of emergence rate and fresh-weight of cultivated rice were only38.06%and 39.96%,respectively.However,cultivated rice showed heavy injury when sown before spraying.At the lowest dose of 150 g（a.i.） /hm^2,the inhibition rate of emergence rate and fresh-weight of cultivated rice reached up to 88.77%and 45.52%,respectively.When sprayed under flooded conditions,oxadiazon completely control weedy rice emergence,and also inhibited emergence of cultivated rice as well.Field trial results showed that application of oxadiazon at 300,450,600 g（a.i.） /hm^2,the plant control efficacy of weedy rice were 26.88%,43.54%,44.45%,respectively,and the control efficacy of fresh weight were 11.58%,20.16%and 27.33%,respectively,under dry direct-seeded conditions;the plant control efficacy of weedy rice were 84.88%,85.74%,90.92%,respectively,and the control efficacy of fresh weight were 30.86%,53.68%,80.15%,respectively,under water directseeded conditions.The yield of the cultivated rice significantly increased when application dose was higher than 450 g（a.i.） /hm^2 under dry direct-seeded cultivation or 300 g（a.i.） /hm^2 under water direct-seeded cultivation.The best way is to spray oxadiazon at 300 g（a.i.） /hm^2 after soil preparation under water direct-seeding and sowing when there is no plash on the soil surface.The water layer should be established but not submerge the lobus cardiacus of rice seedlings.